Method of making thermometer bulbs



F MAKING THERMOMETER BULBS Filed Nov. l2, 1920 M lo 0 s, ,1o. M

0 o m s Patented Nov.' 20, 1923.A

TUNITEDl sTATl-:s

A A1,474,403. PATENT oFFlcE.

LEE F. CHANEY, -OF SPRINGFIELD, OHIO, ASSIGNOB TO THE CHANEY MANUFACTUR-ING COMPANY, OF SPRINGFIELD, OHIO, A CORPORATION OF OHIO.

METHOD OE MAKING THERMOMETER BULBS.

Application le'd November 12, 1920. Serial No. 428,658.

To all whom. it' may concern:

Be it known that I, Lne F. CHANEY, a lcitizen of the United States,residing at Springfield, in the county of Clark and State of Ohio, haveinvented certain new and useful Improvements in Methods of -MakingThermometer Bulbs, of which the following is a specification.

This invention relates to thermometers of the type known as insulatedthermometers, and generally designated as dairy or floatingthermometers, and more particularly to a method of manufacturing thesame, whereby the process of production of such devices will not only besimplified, but will be cheapened without impairing their efficiency andwhich will enable uniformity of production and afford an instrumenthaving a reenforced bulb, of maximum strength.

A further object of the invention is to afford a process whereby suchinstrument may be rapidly and accurately produced by' unskilled laborwith minimum losses, from distortion and breakage of the parts.

With the above primary and other incidental objects in view as will morefully appear in the specification, the invention consists of thefeatures of construction, the steps and operations and the sequence andcombinations thereof, or their equivalents, as hereinafter described andset forth in the claims.

Referring to the drawings, Fig, 1 is a side elevation of the completedthermometer. Fig. 2 is a detail sectional view showing the preparationof the insulating or casing tube. Fig. 3 is a detail View illustratingthe preparation of the capillary tube, having a punctured bulb. Fig. 4illustrates the assembly of the capillary tube and casing tube prior tofusing. Fig. 5 is a detail sectional view of the united capillary andcasing tubes after completion of the fusing operation. Fig. 6illustrates a modification of the construction shown in the precedingfigures. Fig. 7 illustrates the reinforcement of an ordinary thermometerbulb by the herein described process. v p Like parts are indicated bysimilar characters of reference throughout the several views.

A thermometer of lthe insulated o r float-- ing dairy type as shown inFig. 1 comprises an outer or casing tube 1, enclosing the capillary tube2, which is integrally united with the outer or casing tube thru acommon bulb 3. The lower portion of the casing tube 1 surrounding thecapillary tube 2 is usually weighted by means of shots, lead or otherballast material, 4, which is retained in place by a deposit of wax 5vor some adhesive. Inserted within the casing tube 1,

and adjusted to proper relation with" the column of indicating fluid,whether mercury, or alcohol, orvother fluid, within the capillary tube2, is a graduated paper scale 6, upon which is indicated by the heightof the column of indicating liquid within the capilla tube thecorresponding temperatures.

eretofore various methods of manufacturing these insulated or floatingdairy thermometers have been in use. The predominating step in themanufacture of such devices has been that of forming the bulb Y 3 uponthe exterior or casing tube and uniting the capilla tube 2 therewith.Various rocesses haverbeen employed to this end. e of the popularmethods has `been to expand or flare the lower end of the capillarytube, and to unite the edge ofsuch flared or expanded portion with thewall of the casing tube adjacent to the lower end ,thereof andsubsequently blow or otherwise form the bulb 3 from the wall of thecasing tube, below the zone of cohesion of the capillary tube thereto.

A variation of this method also commonly employed has been to firstproduce by blowing or otherwise a bulb upon the extremity of thecapillary tube, which is then inserted within the casing 0r insulatingtube 1. The bulb upon the capillary tube 1n this process in onlytemporary. The adjusted tubes are then heated to fuse them one to theother, and the bulb upon the capillary tube is bursted or ruptured byblowing thru the small end of the capillary tube, While the bulb is in aheated or plastic condition. It will be understood that the capillarytube projects beyond the extremity of the casing tube at this stage ofthe manufacture. After the bursting or dissipation of the bulb upon thecapilla tube, b such blowing operation, the p'rrmanentybulb is thenformed from the material of the outer or casing tube 1. This skill asdoes tlat of fiaring the end of the capillary tube preparatory touniting it with the casing tube. Moreover, both processes rocessrequires considerable;

\ casing tube are caused to unite.

adord a bulb having comparatively thin walls, inasmuch as the bulb isformed by stretching the material of the casing or outer tube, and hencereducing its thickness. The bulb walls thus consist of a single reducedthickness of material. Another diiiculty ot these processes has been thedifficulty of securing uniformity of capacity in the manipulation olfthe wall of the larger tube in forming such bulb The present process isdesigned to overcome these dimculties, and to a'ord a method by whichthese thermometers may be economically and rapidly produced byl fpersons unskilled in glass blowing. To this end, the outer or casingtube l is prepared by drawin one end to a suitable taper, as shown inig. 2 leaving the end ot such tapered portion open as at Z. Thecapillary tube 2 is prepared by blowing or otherwise .forming at one endthereof, a closed bulb 8 as is commonly employed in the ordinary typeof' thermometers. While the bulb 8 of the capillary tube 2, is still in-a plastic condition or upon reheating the bulb subsequent to itsformation, the bulbdis punctured as shown at 9. This puncture is acomparan tively smallvent, and may be eected without destroying thesymmetry of the bulb by various methods. @ne of these methods, andperhaps the most convenient is to provide in the table or bench of theworker, an upstanding wire pin or stud, upon which the finished bulb maybe thrust while still in a plastic condition, thereby causing such pinor stud to puncture the bulb to al'ord the vent 9. Another convenientmethod of forming such vent or opening 9, is to touch the bulb to a hotmetal plate or other heated support havin thereon a suitable glass bait,and then pul ing the bulb away, thereby pullin a portion of the materialfrom the "wall o the bulb, leaving the hole or Vent 9 i A. third methodwhich has been therein. used with success is to fuse the hole or vent 9in the bulb by means of a pin flame direct- The capillary tube with theed thereon. punctured bulb 8 is then inserted within the outer or casingtube 1 until the bulb fits closely within the tapered. extremity of suchcasin tube, and the adiusted tubes are subjecte to fusing heat. In thisfusing operation, the wall of the bulb and the wall of the The wall ofthe casing tube being more directly subjected to the heat, becomesplastic first, and to a greater degree. Under the action of the fusingheat the wall of the casing tube is deflected inwardly into conformitywith the bulb 8 of the capillary tube, which in reality forms a core orform about which the .i wall of the outer or casing tube is shaped.

ln this fusing operation, the terminal opening 7 of the casing tube isclosed or sealed in many instances before the casing tube has nea/incaneath the bulb 8 and within the closed end oit the casing tube as at 13Fig. ll. llt is to provide for the escape oit such entrapped air orgases, that the vent 9 is provided in vthe bulb 8. By the presentprocess, any a1r which may be so entrapped escapes thru the vent 9 andthence outward thru the capillarytube 2, as the walls of thecasing tubegradually close over the bulb 8. The Wall of the casing tube being'in afused cond1tion also contracts somewhat above the bulb as shown in Fig.5. ln this gure the original position of the tapered end of the casingtube is shown by dotted lines while the ultimate shape ot'- lthe casingtube is shown by solid lines. The tube is finished by drawing out theend of the casing tube, leaving the usual teat 10 which eectually closesthe orice 'or vent 9 in the bulb. By this construction it will be seenthat the resulting bulb has walls et double thickness. That is to say,the finished bulb comprises the initial bulb formed upon the capillarytube 2 around which is formed and integrally united therewith, anenclosing bulb formed from the material of the outer or casing tube.This aords a bulb of maximum strength, and moreover the size of suchbulb gaged by that of the inserted bulb- 8, which 'forms the core orlining.

Tn Fig. 6 there is shown a modification in which the perforation 9 isomitted from the initial bulb 8. lln this construction the capillarytube 2 with the bulb 8 intact, is inserted within the tapered portion ofthe casing tube l, which tapered portion is of such size or cut 0H tosuch proportion that ythe bulb 8 approaches quite closely to the ex-A/tremity ofrthe tapered end of the casing The relation of the bulb tothe end,

tube. of the casing tube is such that the material of fthe taperedcasing walls projecting beyond the bulb 8 is insuflicient tocompletelycover the bulb when fused. The relation of the tapered walls of thecasing tube is shown in dottedlines prior to fusing and in solid linesafter completion of the fusing operation. By this relation andproportion of parts, the fusing of the casing tube does not completelyclose oil", any cavity or recess nor trap any body of air. To thevcontrary there is afforded in the partially completed product acent-ral orifice l1 thru which any body of air or-heate-d gas mayescape. ln other Vwords the walls of the casing tube donot Mtl lll

the glass rod and partially completed tube to ladhere and then pullingout the fused portion of glass to form the teat 12.

In the event that it is found that the bulb is notl of sufficient size,it may be increased by heating and blowing thru the capillary tube 2 inthe usual manner, without however, rupturing orbreaking the bulb as hasheretofore been the practice. Thus after the inner core bulb or liningand the outer cas- 'ing have been united, to form a double from the bulb8 into the passageway of the lcapillary tube. 2 is maintained perfectlysmooth, even and` uniform, the bore of the capillary tube and the recessof the bulb 8 merging uniformly and gradually one into the other, whichfacilitates the subsequent steps of exhausting4 the air and moisture orgases from the bulb and tube.v After the bulb has been completed, asherebefore described, the capillary tube and bulb are filled withindicating liquid, by any of the usual orwell known processes, -as forinstance, by the process described in my prior Patent No. 1,345,347,issued July 6,1920, and the tube is calibrated and the scale adjustedthereto in uniformity with said calibration, by any suitable calibratingprocess, as foro instance as described in my prior` Patent No.1,391,878, issued September 27, 1921.

rfhe exhaustion of air and gas and subsequent lling of the tube andcalibrating thereof having been completed, the capillary tube isfinished by closing the upper or outer end thereof, by fusing the same,and the end of the casing tube is also closed by fusing in the usualmanner.

i The method heretofore described may be utilized for reinforcing thebulb of an ordinary thermometer tube as shown in Fig. 7, wherein a shortglass tube 14: is fused into conformity with the bulb 8 as indicated at15 to afford walls of increased thickness, to compensate vfor thestretching of the walls of the ordinary bulb due to the expansion of thematerial in its formation.

By the herein described process, thermom eters of the type heretoforedescribed, are produced rapidly and economically by persons unskilled inthe glass blowing art, and with minimum losses from breakage or dis-ltortion. While the preferred mode of procedure has been shown anddescribed, it will be understood that the invention is not limited tothe exact details, nor specific steps, and changes therein andmodifications thereof, may be made withinl the legitimate and validscope of the appended claims without departing from the spirit of theinvention or sacrificing its advantages.

Having thus described my invention, l claim:

1. The herein described process of producing a thermometer tube,comprising pro..- viding a casing tube, and a capillary tube, forming abulb upon one end of the capillary tube inserting the bulb of thecapillary tube within the casing tube, heating the portion of the casingtube enclosing the bulb and utilizing the bulb as a form or core towhich the casing tube is made to conform and adhere to a'oifd areinforced bulb common to both tubes.

2. rllhe herein described process of producing thermometers comprisingproviding a casing tube and a capillary tube, forming a bulb upon theextremity of the capillary tube, inserting the capillary tube and bulbwithin the casing tube and contracting the casing tube about thecapillary tube bulb with which it is integrally united.

3. rfhe herein described process of producing a thermometer tubecomprising providing a casin tube, inserting the capillary tube 'bulbwithm the casing tube and utilizing the bulb as a core or form aboutwhich the casing tube is shaped, and to which it is integrally united.

4. rilhe herein described process of producing a thermometer tube,comprising providing a casing tube and a capillary tube, forming a bulbwithin the casing tube and utilizing the bulb as a core or form aboutwhich the casing tube is shaped, and providing a vent for the escape ofair and gases from intermediate the bulb and casing tube during theshaping process.

5. The herein described process of producing thermometer tubescomprising providing a bulb upon one end of a capillary tube and acasing tube one end of which is tapered, puncturing the bulb, insertingthe punctured bulb within the tapered portion of the casing tube,heating the portion `of the casing tube enclosing the bulb and causingit to conform to and unite with the bulb and seal the puncture therein.

6. The herein described method of forming thermometer tubes consistingin providing a bulb at one end of a capillary tube inserting such bulbwithin a casing tube, an subsequently forming a bulbupon the casing ubearound and enclosing the capillary tube ulb.

7. TheA herein described method of reinforcin thermometer tube bulbs,consisting in ut' izing the bulb as a core or form and ne I l u i inmuneshaping an exterior shell about such bulb in utilizing the bulb 'as alcore or form and .with which the shell is integrally united by shapingabout such bulb an exterior adherfusing. ent shell, and providing a ventfor lthe l5 8. The herein described method of reinescape of air andgases from between the 5 forcing thermometer tube bulbs, consistingshell and bulb during the formingoperation.l in puncturing the bulb, andforming a shell ln testimony whereof, .l have hereunto about theexterior of the bulb and over the set my hand this 5th day of NovemberA. l). puncture thru which heated air and gases 1920. r

may escape from such shell during the v V LElElF. CHANEY. 10 forming'operation. Witnesses. V

9. 'The herein described method of rein- W. F. HEROLD.

forcing thermometer tube bulbs, consisting, JOHN B. MGGREW.

